The law, enacted this year, made it a crime for unauthorized migrants to enter the state. Challengers say immigration is a federal matter.

Washington — The Supreme Court on Wednesday left in place a block on a new Florida immigration law that imposes criminal penalties on migrants who are in the U.S. illegally and enter into the state, with the justices declining to pause a lower court decision that stopped it from taking effect while legal proceedings move forward.

The Supreme Court appeal arose from a challenge to Florida’s enforcement of a new law targeting undocumented migrants.